2002 年 43 巻 7 号 p. 1469-1474
The temperature dependences of the nuclear-electric-quadrupole frequency ωQ of 117In and 111Cd doped in ferroelectrics LiTaO3, Li1−xInx⁄3TaO3 with x=0.2, and Li1−xCdx⁄2TaO3 with x=0.167, measured by the perturbed-angular-correlation technique, indicate that In behaves like Li; further, in a certain temperature range above the phase-transition temperature, a local system consisting of In (Li) and oxygen ions is very stable, by taking resonance structures, whereas Cd does not behave like Li, and a system consisting of Cd and oxygen ions does not take resonance structures, because the ionic size of Cd is large. It is considered that the resonance structures are due to a disordering of the oxygen ions, and that the order-disorder of oxygen ions is the driving mechanism for ferroelectric instability in the LiNbO3–LiTaO3 system.
